Hughes AIM-4 Falcon

Development of a guided air-to-air missile began in 1946. The original purpose of the weapon was as a self-defense weapon for bomber aircraft, but after 1950 it was decided that it should arm fighter aircraft instead, particularly in the interception role. The first test firings took place in 1949, at which time it was given the popular name Falcon. The initial models entered service in 1956.

Hughes produced the AIM-4 in both heat-seeking and radar-guided versions. The USAF conducted F-4 trials with the AIM-4D in late 1965. Lacking proximity fusing, the missile would only detonate if a direct hit was scored. The missile served during the Vietnam War with USAF F-4 Phantom units. Only five kills were recorded. The main problem of the missile was cooling of the seeker unit. The limited amount of on-board coolant meant that the seeker could not be pre-cooled for any length of time. This meant that it had to be cooled shortly before firing, so that most targets were out of reach again when the missile was finally ready.

A total of about 26,000 of the infrared-homing Falcons were built. The AIM-4D was gradually withdrawn from use beginning in 1969, and by 1973, the AIM-4D was no longer operational with the USAF.